The camera, we are told, doesn’t lie. But, as we also know, it can shade, twist, nudge and otherwise distort our impressions of the things it shows us.

Documentary films, for instance, are non-fictional in that the people who make them do not, as a rule, stage or manipulate the events they film. But whether documentaries are undisputed records of ‘the truth’ is not clear.

Documentarians are drawn to their subjects because they have ideas and opinions about them, after all, and the people whom they film grant access to their lives and words in pursuit of agendas of their own. Even when it’s entirely truthful, a documentary is a work of creativity and imagination, and the impressions that it creates are inevitably infused with somebody’s point of view or perspectives.

And yet, enough can emerge through the filter of subjectivity for us to feel that we can intuit what’s real about the subject. Two films opening today bring these questions to bear within the confines of what we might call the biodoc: a filmed portrait of a notable individual.

“Conan O’Brien Can’t Stop” is a chronicle of a nationwide performance tour which the TV talk show host undertook in 2010 after he was given the reins of NBC’s “Tonight Show” and then summarily replaced six months later by his predecessor, Jay Leno. “Buck” is the story of Buck Brannaman, a horse trainer who drives himself around the USA gentling unruly animals (and, just as often, their owners) and teaching and practicing the philosophy of Natural Horsemanship (aka, horse whispering).

The films focus on men of strong personality and unusual accomplishments, and they pose the question of how the persona revealed in a documentary relates to the actual living human being in the spotlight.

Actually, spotlight is a funny term here, because Brannaman, despite enjoying national fame as a trick-roper when he was boy and working alongside Nicholas Evans and Robert Redford on the book and film, respectively, of “The Horse Whisperer,” is a solitary, humble and altogether spotlight-averse fellow. He granted first-time documentarian Cindy Meehl access to his whole life: childhood photos, films and memories, conversations with his foster mother, his wife and his daughter, long chats on long drives, and, most impressively, his horse-training clinics and workshops held at various sites around the country. But you sense that it would be just fine with him if nobody ever pointed a lens his way.

The character who emerges in the breezy, somewhat meandering “Buck” is plain-spoken, heartfelt, compassionate, witty, and wise. His horse-training technique is based on understanding the psychology of animals and on attuning his human and equine clients with one another. He can “break” (he hates the term) wild colts by barely touching them, and he can teach riders how to achieve a synchronization of themselves and their horses so that they are, virtually, one animal. Various experts attest that he’s a magician, and the film offers filmed evidence of his craft.

A good portion of “Buck” is spent on revelations of Brannaman’s brutal upbringing. His sadistic, alcoholic father made rodeo and even TV stars of his sons (Buck’s brother, Smokie, is notably absent from the film), and the old man’s cruelty went terribly unchecked after his wife’s early death. The boys were eventually rescued and put into foster care, and it was there, surely, where Brannaman began to develop, if unwittingly, his insights into the roles of brutality and kindness in human and animal learning and behavior.

The film’s most riveting sequence is a long episode involving an untamed stud horse that is, in Brannaman’s words, “as close to a predator as you will ever see”: unruly, vicious, apt to charge and kick and even bite his minders. Brannaman gets to work on him, and the results are illuminating, if not what you might expect. The brief story of the angry yellow horse provides excellent proof of some of Brannaman’s most honored maxims about animals -- human and otherwise. And it leaves you with respect and wonder for a man like very few others.

Conan O'Brien in "Conan O'Brien Can't Stop"

In contrast to Brannaman, Conan O’Brien is viscerally compelled to grab the spotlight, so much so that he put together a stage show and toured the United States (starting in Eugene) when his departure from NBC rendered him legally unable to appear on television for some months. With a gang of writers, a stage band (complete with backup singers) and a string of celebrity surprise guests, he put together something that was part musical (lots of fratboy rock covers), part confessional monologue, part variety show.

The title “Conan O’Brien Can’t Stop” suggests a peek into the compulsions that make O’Brien seek the approbation of audiences by, literally, making a spectacle of himself. But director Rodman Flender (yes, he exists: I checked) only glances behind his star’s psychological curtain fleetingly and incompletely. Rather than dissecting O’Brien’s need to perform, he gives us a fairly static film about the man at work: cajoling and bossing staffers, grousing about travel and accommodations, interacting (often reluctantly) with fans and celebrities, rehearsing, performing, and recovering from each show.

A lot of footage is dedicated to actual performances, so you can get quite your fill of O’Brien the singer/guitarist/dancer/comic. And a lot consists O’Brien’s ranting and complaining backstage or at home or while traveling -- sequences in which, I note with chagrin, very little funny is said. O’Brien may have been responsible for some great comedy as a writer for “The Simpsons” or on his own show, but as an ad-libber he’s flat, even when writing comedy.

Despite that flaw, he insists on being rewarded with the laughter of employees and audiences for his not-so-bon mots, revealing a larger issue that the film dances around but doesn’t fully address -- namely, O’Brien comes off as brittle, vain and thin-skinned: a jerk, in short. He may be ideal for the work he does, in which false sincerity and feigned interest are daily bread, but you’re left generally glad that he comes into your home only as a talking head on TV and not in person. Yes, he was going through some changes at the time the film was made. But in comparison to others who struggle against real travails (the young Buck Brannaman, say), he seems spoilt, entitled, impatient, shrill and mean.

It’s purely coincidental that these two films should show up in Portland theaters on the same day. And watching them together makes you wish that O’Brien could have a good long talk with Brannaman. Something, whether inside or out, is riding the talk show host the wrong way, and he could use the horse-trainer’s wisdom and gentling, perhaps, to work through it. Because if these films depict their subjects accurately, the one fellow has made his way through adversity to peace while the other still seems hellbent on driving himself and those around him recklessly on.